Device for subsoil testing and taking of specimens



Jan. 29, 1957 K. SIMON 2,779,195

DEVICE FOR SUBSOIL TESTING AND TAKING OF SPECIMENS Filed April 7, 1955 INVENTOR ffar/ 5/010 BY M g ATTORNEY United States Patent DEVICE FOR SUBSOIL TESTING AND TAKING OF SPECIMENS Karl Simon, Weinheim, Bergstrasse, Germany Application April 7, 1953, Serial No. 347,257 Claims priority, application Germany April 10, 1952 2 Claims. (Cl. 73-421) The present invention refers to a device for testing soil which, above all, permits the taking of undisturbed specimens of soil-substances of all kinds, especially of loose or fluid soils.

The taking of undisturbed specimens of soil is a prerequisite for the exact determination of the structurally technical important properties 'of soil. In the case of non-cohesive, fluid soil substances, e. g. sand saturated with water, the customary connecting pieces for withdrawing samples, such as, core pipes have failed as these kinds of soil flow out of the specimen takers.

Therefore closing contrivances have been devised for taking specimens of this kind, but these closing contrivances exhibit fundamental deficiencies. A mechanical closure does not offer any security against shocks and shaking when drawing specimens. The specimen also cannot be protected from the loss of water as soon as it is lifted above the level of the water in the ground. Therefore attempts have been made to introduce substances into the lower end of the pipe of the specimen taker, which, like cement, or certain chemicals or thixotropic solutions, are capable of solidifying soil substances to form sealing plugs therewith. Also, attempts have been made to prevent the falling out of specimens loosened from the sub-soil by means of an additional core holding contrivance of a mechanical or mechanical-hydraulic kind. Finally, it is known that uncohesive soil materials can be made cohesive by cooling them sufiiciently. As larger areas of sub-soil must be subjected to cold treatment through the circulation of cooling brine for this purpose extensive cooling and prolonged treatment hecome necessary. For this reason the existing process is not suitable for the present purpose, that is for structuralgeological subsoil exploration.

In accordance with this invention, a cross-sectional portion of a specimen is cooled to change its consistency so as to hold the specimen substance in the specimen taker.

Further, a device embodying the present invention for taking core samples or specimens of fluid subterranean earth structures comprises a generally cylindrical body having a tapering lower portion terminating in a cutting edge, a tubular core forming member or socket within the body and spaced radially from the inner surface of the later to define an annular space around the core forming member, the lower edge of the latter terminating above the cutting edge of the lower portion of the outer body, a hollow freezing ring disposed within the lower portion of the outer body between the core forming memher and the cutting edge and having a downwardly tapering cross-section with the inner surface of the hollow freezing ring being cylindrical and registering axially with the cutting edge and with the inner surface of the core forming member, the hollow ring opening upwardly into the above-mentioned annular space, conduit means extending through the annular space to the interior of the hollow ring for supplying compressed refrigerant to the 2,779,195 Patented Jan. 29, 1957 ice latter, and means communicating the annular space with atmospheric pressure so that the compressed refrigerant undergoes a pressure drop in escaping from the hollow ring into the annular space thereby to effect freezing of the fluid constituents of a core sample or specimen of earth structure taken into the core forming member at the bottom of the latter. Preferably, the core forming member of the above-described construction is formed of a transparent material thereby to permit observation of the core sample within the core forming member.

By generating cold in the freezing ring it is possible to freeze a small part of the specimen entirely without changing the structure of the rest of the specimen. The specimen is accordingly held by the frozen plug in the core forming member connecting piece by this means.

The above arrangement, besides permitting the taking of fluid soil materials, also allows an important survey to be made in undisturbed subsoil which was impossible heretofore. Thus, by comparison of the water content of the frozen and unfrozen specimens and the sensitivity to frost of the soil materials can be ascertained in situ. A temperature responsive element may be installed in the cutter to permit the taking of the temperature of the water and the soil and the control of the freezing process.

Furthermore, the arrangement permits determinations to be made of the functional relation between the temperature and the tenacity of the fluid soil together with the value of its permeability to water. The above, and other objects, features and advantages of the invention will be apparent in the following detailed description of an illustrative embodiment thereof which is to be read in the accompanying drawing showing a side elevational view, partly broken away and in section, of the illustrative embodiment.

Referring to the accompanying drawing in detail, it will be seen that a device embodying this invention in cludes a generally cylindrical body 2 having a tapering cutter ring I screwed on the lower end thereof, and a tubular core forming member or socket 3 which is disposed within the body 2 and spaced radially from the inner surface of the latter to define an annular space 14 around the core forming member. Further, it will be seen that the lower edge'ot the core forming member 3 terminates above the cutting edge of the cutter ring 1. The withdrawal connecting piece or body 2 is connected with the rods 5 by way of a rod coupling 4. The pressure of the rods 5 is transmitted by the pressure plate 6, while the pull of the rods is transmitted to the body 2 by a stretching ring 7, tension cone 8 and tension wedges 9. The socket or tubular core forming member 3 is held at the top by the socket plate 10, and at the bottom by the socket ring 11. Under the pressure of the rods 5 the cutter 1 continuously penetrates the undisturbed soil, and, with the illustrated construction, the pressure is transmitted to the walls of the resulting hole in an almost vertical direction, while the cylinder of soil, cut out by the circular front cutting edge, is led into the inside of the core forming member 3 without any additional lateral pressure.

A hollow freezing ring 12, conically tapered toward the bottom is fitted in the cutter body 1, with the inner cylindrical surface of the ring 12 registering axially with the inner surface of tubular member 3, and with the edge of the cutting ring 1. The hollow ring 12 opens upwardly into the annular space 14.

The cooling of the soil substance and the speed of the regulated transfer of cold into the soil substance can he arrived at in various methods and can be controlled. For instance, in the illustrated embodiment, highly compressed carbonic acid is led into the freezing ring 12 from the upper surface through metal capillaries 13, and from a ars.

there the pressure is decreased to atmospheric pressure through the annular space between body 2 and tubular member 3 and the hose connection 15. The connecting piece or body 2 is made of steel, while the tubular memher 3, which is only stressed by -the wall friction of the penetrating soil substance, can be of sheet metal, hard paper or transparent plastic, which should be hard and scratch-proof and have a low coeificient of friction in contact with sand and clay. The transparent socket or tubular member 3, made of "a suitable synthetic plastic material, e. g. derivatives of cellulose or artificial resin, permits viewing of the taken specimen from the outside; and it can be used repeatedly or be cut open in order to obtain the specimen without requiring the pressing of the latter from the core forming tubular member.

There is filter platelfi in the socket plate It), through which the water from the pores of the specimen across the entire cross-section of the socket or tubular member 3 can enter the interior of the rods,-sealed by packing rings 17, when filter-testing, whereby the casing can be used for measuring the ground water entering during an interval of time or, in case of layers above the groundwater, for measuring dripping filling water. Before beginning the filtering test it is possible to free the sludge chamber 18 of deposited soil substances by means of the suction basket 19 of a pump, which is at the upper surface. If occasion arise one can use rinsing water to clean out the sludge chamber.

Although an illustrative embodiment of the invention has been described in detail herein and illustrated in the accompanying drawing, it is to be understood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein without departing from the scope or spirit of the invention, except as defined in the appended claims.

I claim:

1. A device for taking core. samples of fluid subterranean earth structures which comprises a generally cylindrical body having a tapering lower portion terminating in a cutting edge, a tubular core forming member within said body and spaced radially from the inner surface of the latter to define an annular space around said core forming member, the lower edge of said core forming member terminating above said cutting edge of said lower portion of the-body, a hollow freezing ring disposed within said lower portion of the body between said core forming member and said cutting edge and having a downwardly tapering cross-section with the inner surface of the hollow ring being cylindrical and registering axially with said cutting edge and the inner surface of said core forming member, said hollow ring opening upwardly into said annular space, conduit means extending through said annular space to the interior of said hollow ring for supplying compressed refrigerant to the latter, and means communicating said annular space with atmospheric pressure so that the compressed refrigerant undergoes a pressure drop in escaping from said hollow ring into said annular space to effect freezing of the fluid constituents of a core. sample of earth structure taken into said core forming member at the bottom of the latter.

2. A device according to claim 1; wherein said core forming member is formed of a transparent material to permit observation of the sample therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,109,446 Melberg Sept. 1, 1914 1,870,696 Taylor Aug.- 9, 1932 2,539,355 Reichertz Jan. 23, 1951 2,617,296 Wisenbaker Nov. 11, 1952 FOREIGN PATENTS 329,896 v Germany Dec. 1, 1920 

